2. Core Concepts
• Expose attributes that can be accessed by HAP clients.
• Accept incoming requests from clients and send responses.
• Send notifications to registered clients.
2.5.3 HAP Accessory Objects
An HAP accessory object represents a physical accessory on an HAP accessory server. For example, a thermostat
would expose a single HAP accessory object that represents the user-addressable functionality of the thermostat.
2.5.3.1 Required Services
An HAP accessory object must include at least one service, public.hap.service.accessory-information, as defined in
2.5.3.2 Bridges
A bridge is a special type of HAP accessory server that bridges HomeKit Accessory Protocol and different RF/transport
protocols, such as Zigbee or Z-Wave. A bridge must expose all the user-addressable functionality supported by its
connected bridged endpoints as HAP accessory objects to the HAP controllers. A bridge must ensure that the instance
ID assigned to the HAP accessory objects exposed on behalf of its connected bridged endpoints do not change for
the lifetime of the server/client pairing.
For example, a bridge that bridges three lights would expose four HAP accessory objects: one HAP accessory object
that represents the bridge itself that may include a firmware update service, and three additional HAP accessory
objects that each contain a Light Bulb service.
A bridge must not expose more than 150 HAP accessory objects.
Any accessories, regardless of transport, that enable physical access to the home, such as door locks, must not
be bridged. Accessories that support IP transports, such as Wi-Fi, must not be bridged. Accessories that support
Bluetooth LE that can be controlled, such as a light bulb, must not be bridged. Accessories that support Bluetooth LE
that only provide data, such as a temperature sensor, and accessories that support other transports, such as a ZigBee
light bulb or a proprietary RF sensor, may be bridged.
2.5.3.3 Primary HAP Accessory Object
The HAP accessory object with an instance ID of 1 is considered the primary HAP accessory object. For bridges, this
must be the bridge itself.
2.5.3.4 Colocation
The services contained within an HAP accessory object must be collocated. For example, a fan with a light on it would
expose single HAP accessory object with three services: the Required Accessory Information service, a Fan service,
and a Light Bulb service. Conversely, a bridge that bridges two independent lights that may be in different physical
locations must expose an HAP accessory object for each independent light.
2019-07-26 | Copyright © 2019 Apple Inc. All Rights Reserved.
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